1. Field of the Invention
The present invention relates generally to radio frequency (RF) transmitters.
2. Background Art
Commonly, to ensure compliance with spectrum emission requirements, the supply voltage provided to the power amplifier (PA) in an RF transmitter is increased by a margin above the nominal supply voltage necessary to produce the desired output power of the PA. The margin accounts for variations in temperature, process (i.e., part-to-part variations), and load impedance. For example, commonly, the PA supply voltage is increased so as to achieve a 5 to 6 dB margin in the spectral mask measurements. However, the added margin increases the power dissipation of the PA beyond what is needed to generate the desired output power under nominal conditions.
The present invention will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.